Circulating system for steam-boilers.



No. 753,991. PATENTED MAR. 8, 1904.

W. J. MACDONALD. GIRGULATI-NG SYSTEM FOR STEAM BOILERS.

APPLIUATION FILED NOV. 5; 1903.

N0 MODEL.

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UNITED STATES Patented March 8, 190 i.

PATENT OEETcE.

CIRCULATING SYSTEM FOR STEAM-BOILERS.

SPECIFICATION forming part of Letters Patent No. 753,991, dated March 8,1904.

Application file. November 5, 1903. Serial No. 179,922 (No model.) i

To all whom it may concern:

Be it known that I, WILLIAM J. MACDONALD, a citizen of the UnitedStates, residing at Detroit, in the county of Wayne, State of Michigan,have invented certain new and useful Improvements in Circulatory Systemsfor Steam- Boilers; and I do declare the following to vbe a full, clear,and exact description of the invention, such as will enable othersskilled in the art to which it appertains to make and use the same,reference being had to the accompanying drawings, and to the figures ofreference marked thereon, which form a part of this specification.

This invention relates to a circulatory system for steam-boilers; and itconsists in the construction and arrangement of parts hereinafter fullyset forth, and pointed out particularly in the claims.

The object of the invention is to provide means for producing a freecirculation of water in a steam-boiler of the Scotch type, whereby thecool water at the bottom of the boiler below the furnace may be carriedupwardly and deposited in the upper portion above the flues, therebymaintaining all parts of the boiler at practically the same temperatureand avoiding unequal expansion.

The above object is attained by the structure illustrated in theaccompanying drawings, in which-- V Figure 1 is a diametrical sectionalview through a steam-boiler involving my invention as on line 1 1 ofFig. 2. Fig. 2 is a partial longitudinal section as on line 2 2 of Fig.1.

Referring to the characters of reference, 1 designates the shell of theboiler, which is herein illustrated as of the double-furnace type,having the fire-spaces 2, as commonly constructed. At the rear of eachfire-space is a combustion-chamber 3, having a crown-sheet 4:. Crossingtransversely the upper portion of each combustion-chamber is atube-sheet 5, in which the rear ends of the fines 6 are expanded.

Passing vertically through each of the combustion-chambers and expandedat their upper ends in the crown-sheet 4 are the tubes 7, whose lowerends curve forwardly, downwardly, and laterally and are expanded in the-9 at the bottom of the boiler, thereby establishing a communicationbetween the waterspace 9 and the upper portion 10 of the boiler.

The caloric current from the furnaces passes rearwardly over thebridge-wall 11 and impinges upon I the tubes 7, thence upwardly aroundsaid tubes, and forwardly through the flues 6. This contact of the heatwith said tubes 7 tends to rapidly bring the water therein to a hightemperature and causing an upward circulation of the water therethrough.This upwardmovement of the water in the tubes draws the water from thespace 9 at the bottom of the boiler and induces a circulation whichmaintains all of the water in the boiler at comparatively the sametemperature, so that unequal expansion is obviated. For the purposeofacceleratingthe circulationthrough the tubes 7 while getting up steamand before the boiler is under pressure a steam-pipe 12, connected withanother boiler or source of steam-supply (not shown) is passed throughthe shell of the boiler at the bottom and provided with the branches 13,extending into the tubes 7 whereby a jet of steam may be introduced intothe lower ends of said tubes to cause a more rapid circulation of thewater therethrough, as will be well understood. By means of thisarrangement the cold stratum of water which is usually present at thebottom of boilers of this type, especially at the starting of the firesin the furnaces, is obviated, for the reason that the circulation ofwater which is induced through the tubes 7 as soon as the caloriccurrent comes into contact therewith carries the water from the lowerspace 9 of the boiler and discharges it into the upper portion thereof,drawing the water from the sides of the boiler to maintain thecirculation, whereby the uneven temperature which ordinarily exists isovercome and injury to the shell and to the interior sheets of theboiler by unequal expansion is obviated.

Having thus fully set forth my invention, what I claim as new, anddesire to secure by Letters Patent, is

1. In a circulatory system for steam-boilers, the combination with theboiler-shell and combustion-chamber the top of said chamber having acrown-sheet, of the circulatory tube expanded in the crown-sheet of saidchamber at its upper end, passing downwardly and for- Wardly through thecombustion-chamber in the rear of the furnace and expanded in the lowerwall of said chamber at its lower end, the lower end of said tubecommunicating with the water-space below the combustion-chamber, and theupper end of said tube communicating with the water-space in the upperportion of the boiler.

2. In a circulatory system for steam-boilers, the combination with theboiler-shell, the furnace and combustion-chamber, the top of saidcombustion-chamber having a crown-sheet and a bridge-wall dividing thecombustion-chamber from the furnace, circulatory tubes expanded at theirupper ends in the crown-sheet of the combustion-chamber, said tubesextending downwardly through said chamber and forwardly to a point inthe rear of the bridge-wall, their lower ends being expanded in thesheet forming the bottom of said chamber,said tubes establishingcommunication between the water-space below the furnace and thewater-space in the upper portion of the boiler.

3. In a circulatory system for steam-boilers, the combination with theboiler-shell, the furnace and. the combustion-chamber, a circulatorytube passing through the combustionchamber communicating at its upperend with the water-space of the boiler and at its lower end with thewater-space below the combus tion-chamber, and a steam-pipe entering thelower end of said tube and standing therein free from the walls thereof.

In testimony whereof I sign this specification in the presence of twowitnesses.

WILLIAM J. MACDONALD.

Witnesses:

O. H. WILSON, J r., A. C. J OYGE.

